A linked list is a collection of nodes. Each node contains data and a pointer to the next node.
A linked list is preferred over other data structures like arrays because it has a dynamic size and it's easier to insert and delete elements/nodes.
class Node: def __init__(self, data): self.data = data self.next = None class SinglyLinkedList: def __init__(self): self.head = None self.tail = None def print_ll(self): temp = self.head while temp: print(str(temp.data)) temp = temp.next def insert(self, data): node = Node(data) if not self.head: self.head = node else: self.tail.next = node self.tail = node l1 = SinglyLinkedList() l1val = [1,2,3,4,5] for i in l1val: l1.insert(i) l1.print_ll()
In a linked list, the
head attribute refers to the first node of a list. All the functions used in the list are added in the
Node class is used to create a new node, each node has a
data attribute and a
pointer attribute to the next node which initially points to a null.
Consider two linked lists that will meet at some point. The head nodes of both lists are given pointers to find the node where the two lists merge.
In the above example, the two lists merge at Node 4, which is the result of the function.
In the program below, we use the
merge_point() function to find the data of the node where both the lists merge.
class SinglyLinkedListNode: def __init__(self, data): self.data = data self.next = None class SinglyLinkedList: def __init__(self): self.head = None self.tail = None def insert(self, data): node = SinglyLinkedListNode(data) if not self.head: self.head = node else: self.tail.next = node self.tail = node def merge_point(head1, head2): data =  while head1 != None: data.append(head1) head1 = head1.next while head2 != None: if head2 in data: return (head2.data) head2 = head2.next l1 = SinglyLinkedList() l1val = [1,2,3,4,5] l1_count = 5 for i in l1val: l1.insert(i) l2 = SinglyLinkedList() l2val = [9,2] l2_count = 2 for i in l2val: l2.insert(i) ptr1 = l1.head; ptr2 = l2.head; for i in range(l1_count): if i < 3: ptr1 = ptr1.next for i in range(l2_count): if i != l2_count-1: ptr2 = ptr2.next ptr2.next = ptr1 print(merge_point(l1.head, l2.head))
We follow the steps below to run the
Lines 21–23: Traverse the first linked list and add all the nodes in a list called
Lines 24–25: Check if any node exists in the
data list to traverse the second linked list.
Lines 25–26: Use an exit condition to return the data of the node which exist in the
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